The invention relates to a valve device for a compressed air supply system of a utility vehicle, and to a compressed air supply system having a valve device of said type.
Utility vehicles having pneumatic components require a compressed air supply system. The compressed air is generally fed by a compressor into an air treatment system where the air which is introduced is cleaned in a filter unit before then finally being supplied via a multi-circuit protective valve for use, for example to the brake system of the utility vehicle.
After certain feed quantities are reached or after certain periods of time have elapsed, it is necessary to clean the filter unit. For this purpose, a regeneration solenoid valve is connected within the air treatment system in such a way that compressed air from storage tanks, either the storage tanks of the service brake circuit or one or more storage tanks provided especially for the purpose, flows through the regeneration solenoid valve and in the reverse direction through the filter unit, before then being allowed to flow, laden with moisture and foreign particles, out of the filter unit and into the atmosphere. During the regeneration phases, the compressor is generally shut off or placed into an idle phase.
It is generally sought for the air drying to take place in as effective and efficient a manner as possible, with this requiring in particular a good utilization of the volume available in the air dryer cartridge. This also relates to the regeneration capacity of the system, wherein the dry air which is supplied to the air dryer cartridge for the purpose of regeneration must be provided in a sufficient quantity.
The object on which the invention is based is that of providing a compressed air supply device with an improved regeneration capacity and an increased degree of integration. The object is achieved by a valve device and compressed air supply system having the valve device according to the invention. Advantageous embodiments of the invention are described herein.
The invention encompasses a valve device for a compressed air supply system, having a control chamber which can be charged with compressed air, a control piston plate which delimits the control chamber, a control piston which is attached to that side of the control piston plate which faces away from the control chamber, which control piston projects into a blow-off valve chamber, which is provided with at least one compressed air port, of a blow-off valve, and a valve plate which delimits the blow-off valve chamber and which can be acted on with force in the direction of a valve seat by a spring and which can be lifted up from the valve seat, in order to open the blow-off valve, by the control piston counter to the force of the spring. The control piston and a valve housing which surrounds the control piston define at least two regeneration valve chambers of a regeneration valve with, in each case, at least one compressed air port, and with the at least two regeneration valve chambers either being separated from one another or connected to one another as a function of the position of the control piston.
In this way, a valve device is provided which has a pneumatically activatable regeneration valve. It is hereby possible to utilize considerably higher regeneration air rates than with regeneration solenoid valves, such that it is in particular also possible to regenerate filter units which have a high filter capacity. Here, reference is made in particular to filter units which have a labyrinthine construction, such that the air to be dried and also the regeneration air cover a large distance through the filter unit. The regeneration air quantity required for such filter units can be provided in a simple manner by way of the valve device according to the invention. At the same time, the valve device according to the invention is particularly expedient on account of an integration of the blow-off valve and regeneration valve. It is sufficient to provide a single control chamber, by means of the pressurization of which both the regeneration valve can be switched and also the blow-off valve can be opened.
It is expediently provided that the regeneration valve chambers are separated from one another when the blow-off valve is closed and are connected to one another when the blow-off valve is open. The regeneration is thus automatically initiated whenever the blow-off valve is opened. Conversely, a regeneration takes place every time the blow-off valve is opened.
Provision may be made for the control piston to have at least one constriction which, in a first position of the control piston, is situated entirely within one of the regeneration valve chambers and, in a second position of the control piston, creates a connection between the at least two regeneration valve chambers. The control piston therefore has a dual function. The control piston firstly acts as a tappet with respect to the blow-off valve; and the control piston secondly has, over the constriction, a control device which enables the regeneration valve function.
Provision may likewise be made for the control piston, which defines an axis by its extent between the control piston plate and the blow-off valve chamber, to have at least one duct with at least two duct openings situated axially offset with respect to one another. The at least two duct openings which are situated axially offset with respect to one another are situated in one of the regeneration valve chambers in a first position of the control piston and are situated in different regeneration valve chambers, such that the duct creates a connection between the at least two regeneration valve chambers, in a second position of the control piston.
The invention is expediently refined in that the control piston is separate from the valve plate. It may likewise be provided that the control piston is formed in one piece with the valve plate.
The invention is expediently refined in that the blow-off valve chamber has at least one second compressed air port. The feed line which is connected indirectly or directly to the compressor is connected to the blow-off valve at the second compressed air port. During the feed phase, the compressed air therefore flows through the blow-off valve chamber with the blow-off valve closed, while in the regeneration phase, an outflow of the air out of the blow-off valve chamber is enabled.
It is expediently provided that the regeneration valve and the blow-off valve are arranged in the same valve housing. This provides a particular degree of integration.
The invention also encompasses a compressed air supply system having a valve device with a control chamber which can be charged with compressed air, a control piston plate which delimits the control chamber, a control piston which is attached to that side of the control piston plate which faces away from the control chamber, which control piston projects into a blow-off valve chamber, which is provided with at least one compressed air port, of a blow-off valve, and a valve plate. The valve plate delimits the blow-off valve chamber and can be acted on with force in the direction of a valve seat by a spring. The valve plate can be lifted up from the valve seat, in order to open the blow-off valve, by the control piston counter to the force of the spring, with the control piston and a valve housing which surrounds the control piston defining at least two regeneration valve chambers of a regeneration valve with in each case at least one compressed air port. At least two regeneration valve chambers either are separated from one another or connected to one another as a function of the position of the control piston. It is possible for the control chamber to be activated by a solenoid valve. The at least one compressed air port of the blow-off valve chamber is connected to a compressed air inlet of a filter unit, and the regeneration valve chambers are connected to in each case one port of a non-return valve which is connected to a compressed air outlet of the filter unit.
It is expediently provided that a second compressed air port of the blow-off valve chamber is connected to a compressed air source.
The invention will now be explained by way of example below with reference to the appended drawings on the basis of particularly preferred embodiments. In the drawings: